This invention relates to core plugs insertable into a web roll core, and in particular, to an expandable core plug for improved gripping of such cores.
In manufacturing and other operations, a roll of material may need to be mounted onto or off a roll. In conventional web treatments where machines handle reels of paper, plastics, metal foils, textiles and other sheet material, the cores of these reels need to be mounted on the machines so that rotational drive can be selectively coupled to the cores to effect winding or unwinding of the web entrained on the cores. The cores carrying the webs are normally tubular components made from cardboard, metal or plastic material. To effect the rotational drive to a core, it is desirable to include a core plug in either end of the core. The core plugs engage and rotatably support the core. Once the core plugs are inserted into the core, the core plugs are mounted on a roll stand which fits into journals of the core plugs.
As stated above, the cores are usually made of heavy paper or cardboard in tubular form. Cores, being made of paper, cannot be held to a close internal diameter tolerance. The cores become xe2x80x9cout-of-roundxe2x80x9d affecting the fit of the core plug into the core. The core and core plug become loose thereby causing the core and core plugs to bang against each other. The looseness of fit between core and core plug can cause significant local stresses in the core to the point that the core structure and core plugs are damaged.
The present invention addresses the problem of prior art core plugs by providing an expandable, self-adjusting core plug which will maintain a fit between core plug and an out-of-round core. The present invention accomplishes this by providing a core plug with a number of individual, elongated beveled ribs and a corresponding beveled spindle, both of which cooperatively and axially adjust the thickness of the core plug to meet variations in the inner diameter of the core.
These together with other objects of the invention, along with various features of novelty which characterize the invention, are pointed out with particularity in this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.